Diamond district jeweler J.B. International is suing Manhattan Buyers Inc., a jeweler that resides in the same building, claiming that Manhattan Buyers shouldn’t have purchased one of J.B.’s diamonds, which ended up stolen after it was thrown in the trash.

According to a complaint filed March 8 in Supreme Court in New York County, in November 2015, an unknown J.B. employee inadvertently discarded more than $4.5 million worth of diamonds, including a 10.11 ct. oval worth $1.5 million. The next month, the jeweler discovered the gems were missing and reported it to the New York Police Department.

About a week later, NYPD investigators discovered that a building security guard had found the diamonds in the trash and didn’t report what he found. He then sold the biggest diamond—the 10.11 ct. stone—to Manhattan Buyers for $70,000, the suit charges. Manhattan Buyers then cut it down to a 9 ct. stone, it added.

The suit alleges that Manhattan Buyers “knew or should have known” the stone was stolen, and that, by recutting the stone, it “vandalized, mutilated, and destroyed” J.B.’s property.

Manhattan Buyers could not be reached for comment. However, in a counterclaim filed in February in a related lawsuit, the company said that it purchased the diamond in good faith and did not know the item was stolen.

When questioned by the NYPD, the company “cooperated in all respects and turned over said diamond to the investigating detectives,” it added.

Its counterclaim accuses J.B. International of negligence for failing to properly supervise its employees.

According to a report in the New York Daily News, in September 2016, the security guard, Wilfred Martinez, pleaded guilty to grand larceny and was sentenced to three years’ probation.

J.B. International’s suit also takes aim at the building’s landlord, management company, and security company, accusing them of “failing to exercise” reasonable care in hiring security personnel for the building.